My ex-wife delayed a court date for maintenance by sending a lawyer with a letter from a psychologist saying she was not fit to travel to court due to very sudden onset of depression.
How many anecdotes are like this?
Especially amongst the youth; kids are pretty impressionable. Even adults up onto around age 25. It's not too hard to convince these people to find a therapist, then self-select specific symptoms to report (all therapy diagnosis is based primarily of self-reported data, not objective data).
It's not too hard to convince even a halfway selfish or self-centered person that they have a specific diagnosis, so they can say "I'm not narcisstic, I'm neurodivergent" or "I'm not a poor learner, I have ADHD/ADD" or "I'm not a lazy worker, I'm suffering from depression".
How many times have you heard this?
No one wants to admit to a character flaw; they'd rather have a sciency-sounding disorder which means that their flaws are not their fault.
People don't want agency when it comes to their flaws; that "flaw" must instead be something outside of their control.